Characterization of relaxin radioimmunoassay using Bolton-Hunter reagent. First results in plasma during pregnancy, and in placenta, corpora lutea and ovarian cysts in woman.

Application of a porcine relaxin radioimmunoassay system using Bolton and Hunter reagent was characterized in different biological fluids. In pregnant woman, plasma reveals concentrations from undetectable values to 1,800 pg/ml. Maximal concentrations are found between the 8th and the 13th weeks of pregnancy. These peak values are significantly different from those at other stages of pregnancy. Appreciable relaxin concentrations are detected in gestational corpus luteum extract, and in corpora lutea cyst fluid of pregnant and nonpregnant women. No relaxin was detected in a cyclus corpus luteum extract, in a placental extract, or in an ovarian serous cyst. The presence of immunoreactive relaxin in the nonpregnant woman is reported.